Isomerization of methylcyclopentadiene dimers

Abstract A commercial mixture of methylcyclopentadiene dimers mainly consisting of four dimeric compounds with partial structures of 1‐methyl‐ and 2‐methylnorbornene, undergoes slow oxidation and isomerization when it is dissolved in CH 2 Cl 2 , CHCl 3 or CCl 4 . Both reactions are simultaneous but independent of each other. Isomerization only concerns those isomers that contain in their structure a 2‐methylnorbornene ring. The nature of the isomerization and the influence of different acid media is studied.